Tubular Fuel Cell Module and Manufacturing Method Thereof

ABSTRACT

A tubular fuel cell module is provided with a tubular cell of a tubular fuel cell, and a heat transfer pipe through which a heating/cooling medium flows to selectively heat and cool the tubular fuel cell. The heat transfer pipe includes a first straight portion, a second straight portion, and a bent portion that connects the first straight portion with the second straight portion. At least a portion of the tubular cell is arranged on at least one of the first straight portion and the second straight portion. As a result, the reliability of a seal of the tubular fuel cell module is improved.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a tubular fuel cell module and a manufacturingmethod thereof. More particularly, the invention relates to a tubularfuel cell module having improved seal reliability and a manufacturingmethod of that tubular fuel cell module.

2. Description of the Related Art

In recent years much research has been done with tubular fuel cells(hereinafter also referred to as “tubular PEFC”) with an aim to improveoutput density per unit volume to at least a certain level. The unitcell of a tubular PEFC (hereinafter also referred to as “tubular cell”)typically includes a Membrane Electrode Assembly (MEA) which has ahollow electrolyte layer and a catalyst layer arranged on both sides(i.e., the inside and the outside) of that hollow electrolyte layer.Electric energy which is generated through an electrochemical reactioninduced by supplying a gas containing hydrogen to the inside of the MEAand a gas containing oxygen to the outside of the MEA is then extractedfrom the unit cell via collectors arranged on the inside and outside ofthe MEA. That is, in a tubular PEFC, generated electric energy isextracted by supplying one reaction gas (such as a gas containinghydrogen, for example) to the inside of the MEA provided in each unitcell and supplying another reaction gas (such as a gas containingoxygen, for example) to the outside of the MEA provided in each unitcell, which means that the same reaction gas can be supplied to theoutside surfaces of two adjacent unit cells. Therefore, a tubular PEFCdoes not require separators which serve to separate the gases and thatare required by a conventional flat plate fuel cell, which enables theunit cell to effectively be made smaller.

Published Japanese National Phase Application No. 2004-505417 of PCTapplication, for example, describes technology related to such a tubularPEFC. More specifically, the described technology relates to a fuel cellin which all of the components of a microcell are fabricated in a singlefiber assembly. The described technology is able to generate highdensity energy output and thus minimize the volume of an electrochemicalcell apparatus (i.e., a tubular fuel cell).

The electrolyte membrane of the tubular cell expresses a protonconducting ability within a predetermined temperature range (such aswithin a range around 80 degrees Celsius, for example). Therefore, whenthe tubular PEFC is operating, the temperature of the electrolytemembrane must be maintained within that temperature range. Accordingly,with a tubular PEFC module having a tubular cell, in order to keep thetemperature of that tubular cell or the electrolyte membrane that formsa part of the tubular cell within the appropriate range, a heat transferpipe is arranged on at least one of the inside and the outside of thetubular cell and the temperature of the tubular cell is regulated bywarming or cooling the tubular cell using a heating/cooling medium thatflows through the heat transfer pipe.

In this way, in a tubular PEFC (module), a heating/cooling medium isalso used in addition to a gas containing hydrogen and a gas containingoxygen so a seal portion which separates the gases from theheating/cooling medium must be provided at, for example, an end portionof the tubular cell or the MEA which constitutes a portion of thetubular cell. In a related tubular PEFC module such as that described inPublished Japanese National Phase Application No. 2004-505417 of PCTapplication, for example, one seal portion is provided for separatingthe two kinds of reaction gases, another seal portion is provided forseparating the reaction gases from the heating/cooling medium, and yetanother seal portion is provided for separating the heating/coolingmedium from ambient air.

However, when the tubular PEFC having the structure described inPublished Japanese National Phase Application No. 2004-505417 of PCTapplication is operated and as a result the temperature of theconstituent elements represented by the tubular cell and the heattransfer pipe and the like rises, the tubular cell and the heat transferpipe expand. As a result, the seal in a tubular PEFC having a complexseal structure in which there are many seal portions tends to be lessreliable.

SUMMARY OF THE INVENTION

This invention thus provides a tubular fuel cell module having improvedseal reliability, as well as a manufacturing method of that tubular fuelcell module.

An aspect of the invention therefore relates to a tubular fuel cellmodule provided with a tubular cell of a tubular fuel cell, and a heattransfer pipe through which flows a heating/cooling medium thatselectively heats and cools the tubular cell. The heat transfer pipeincludes a first straight portion, a second straight portion, and a bentportion that connects the first straight portion with the secondstraight portion. Further, at least a portion of the tubular cell isarranged on at least one of the first straight portion and the secondstraight portion.

A tubular fuel cell module may be provided with a hollow MEA, and a heattransfer pipe through which flows a heating/cooling medium thatselectively heats and cools the MEA; the heat transfer pipe includes afirst straight portion, a second straight portion, and a bent portionthat connects the first straight portion with the second straightportion; and the MEA is arranged on at least one of an outer peripheralsurface of the first straight portion and an outer peripheral surface ofthe second straight portion.

Further, a tubular fuel cell module may be provided with a tubular cellof a tubular fuel cell, and a heat transfer pipe through which flows aheating/cooling medium that selectively heats and cools the tubularcell; the heat transfer pipe includes a first straight portion, a secondstraight portion, and a bent portion that connects the first straightportion with the second straight portion; and the outer peripheralsurface of at least one of the first straight portion and the secondstraight portion contacts the outer peripheral surface of the tubularcell.

Specific examples of the heating/cooling medium include water, ethyleneglycol, and a mixture of the two, for example. As long as the heattransfer pipe is made of corrosion resistant material that can withstandthe operating environment of a tubular PEFC, the constituent material isnot particularly limited. However, it is easier to make the tubular fuelcell module smaller if the heat transfer pipe also serves as an externalcollector or an internal collector so the heat transfer pipe may also bemade of material having excellent electrical conductivity as well asbeing corrosion resistant. Specific examples of material that iscorrosion resistant and also has good electrical conductivity includematerial in which Ti is coated on the surface of Cu (such as Cu—Ti cladmaterial), in addition to Au and Pt. In addition, to effectively improvethe output density of the tubular fuel cell module, the axial directionof the first straight portion and the axial direction of the secondstraight portion in the heat transfer pipe may be parallel with eachother. Further, from the same viewpoint, the tubular cells may bearranged such that the outer peripheral surfaces thereof contact theouter peripheral surfaces of the first straight portion and the secondstraight portion of the heat transfer pipe. The tubular cells may alsobe arranged such that their axial directions are parallel with the axialdirections of the first straight portion and the second straightportion.

Here, the term “hollow MEA” refers to an MEA that includes at least ahollow inside catalyst layer, an outside catalyst layer arranged on theoutside of the inside catalyst layer, and an electrolyte membranesandwiched between the inside catalyst layer and the outside catalystlayer. The MEA constitutes a portion of the tubular cell.

The phrase “the MEA is arranged on at least one of an outer peripheralsurface of the first straight portion and on an outer peripheral surfaceof the second straight portion” means that when the heat transfer pipealso serves as an internal collector, the MEA is formed on (contacts) atleast one of the outer surface of the first straight portion of the heattransfer pipe and the outer surface of the second straight portion ofthe heat transfer pipe, and when an internal collector is providedbetween the heat transfer pipe and the MEA (i.e., when the heat transferpipe does not also serve as an internal collector), the MEA is formed onthe outer surface of the internal collector which is arranged on theouter surfaces of the first and second straight portions of the heattransfer pipe.

According to the foregoing aspect, adjacent first and second straightportions can be connected by the bent portion so a tubular fuel cellmodule can be provided which has an S-shaped heat transfer pipe having nnumber of straight portions and n−1 number of bent portions. In thisway, by forming the heat transfer pipe in an S shape, it is possible tolimit (i.e., reduce the number of) the inlets and outlets for theheating/cooling medium, which in turn enables the structure of the sealportion formed between the reaction gas and the heating/cooling mediumto be simplified. Accordingly, a tubular fuel cell module havingimproved seal reliability by simplifying the structure of the sealportion is able to be provided.

Also, when the heat transfer pipe contacts the inside of the tubularcell (i.e., the inside of the MEA) of the tubular fuel cell, the insideof the tubular cell of the tubular fuel cell, which is particularlyprone to heat build-up, can be efficiently cooled.

In the tubular fuel cell module, the first straight portion, the secondstraight portion, and the bent portion may be formed by bending a singleheat transfer pipe.

The phrase “formed by bending a single heat transfer pipe” means that atleast one portion of the heat transfer pipe is formed in the shape ofthe letter “U”, which includes a first straight portion, a bent portion,and a second straight portion, by bending a single heat transfer pipe.

Forming the first straight portion, the second straight portion, and thebent portion by bending a single heat transfer pipe in this way obviatesconnections between the first and second straight portions and the bentportion, thus further improving the seal reliability.

In the tubular fuel cell module, the inlet and the outlet of the heattransfer pipe may be positioned on the same side with respect to thecenter in the axial direction of the tubular cell or the MEA.

Positioning the inlet and the outlet of the heat transfer pipe on thesame side with respect to the center in the axial direction of thetubular cell or the MEA enables the seal portion that separates thereaction gas from the heating/cooling medium to be formed only on theside where the inlet and the outlet are located, thus enabling thestructure of the seal portion to be easily simplified.

In the tubular fuel cell module, the first straight portion and thesecond straight portion may be arranged on a horizontal plane, and theinlet and outlet of the heat transfer pipe may also be formed facing theoutside in a direction intersecting the axial direction of at least oneof the first straight portion and the second straight portion whenviewed from above the horizontal plane.

An example of a case in which the inlet and outlet of the heat transferpipe is formed facing the outside in a direction intersecting the axialdirection of at least one of the first straight portion and the secondstraight portion when viewed from above the horizontal plane is asfollows. When the inlet of the heat transfer pipe is formed on an endportion of the first straight portion which does not lead into a bentportion and the outlet of the heat transfer pipe is formed on an endportion of the second straight portion which does not lead into a bentportion, the inlet of the heat transfer pipe is formed so as to opentoward the side opposite the second straight portion that is adjacent tothe first straight portion, and the outlet of the heat transfer pipe isformed so as to open toward the side opposite the first straight portionthat is adjacent to the second straight portion. In the invention, theangle formed between the direction in which the inlet and outlet of theheat transfer pipe open and the axial direction of at least one of thefirst straight portion and the second straight portion is notparticularly limited, although making that angle 90 degrees makes iteasier to connect a plurality of the tubular fuel cell modules together.

Accordingly, when a plurality of the tubular fuel cell modules areconnected together, the inlet of the heat transfer pipe of one tubularfuel cell module can easily be connected to the outlet of the heattransfer pipe of another tubular fuel cell module. Therefore, inaddition to the effects described above, a tubular fuel cell module canbe provided which is easier to connect to another tubular fuel cellmodule when a plurality of the modules are provided.

Another aspect of the invention relates to a manufacturing method of atubular fuel cell module provided with at least one hollow MEA, and aheat transfer pipe through which flows a heating/cooling medium thatselectively heats and cools the MEA. This manufacturing method includesthe steps of forming the MEA around a straight tubular member, andforming a heat transfer pipe that includes a first straight portion, asecond straight portion, and a bent portion that connects the firststraight portion with the second straight portion, by bending thestraight tubular member, thus yielding a bent body in which the MEA isformed around the heat transfer pipe. When forming the MBA, it is eitherformed sequentially at intervals the distance of which corresponds to atleast the length of the bent portion, or the MEA formed around at leastthe bent portion is removed after bending the straight tubular member.

Here, the “straight tubular member” refers to the heat transfer pipebefore it is bent to form the bent portion. Furthermore, the method offorming the MEA on the outside of the straight tubular member can bedivided into a case in which the heat transfer pipe formed by bendingthe straight tubular member (hereinafter simply referred to as “heattransfer pipe”) also functions as an internal collector and a case inwhich the heat transfer pipe does not function as an internal collector.In the case where the heat transfer pipe also functions as an internalcollector, the MEA may be formed so that the outer surface of the heattransfer pipe and the inside catalyst layer of the MEA contact oneanother, for example. In order to make it easier to remove the MEAformed at the location corresponding to the bent portion as well as nearthe inlet and the outlet (hereinafter also referred to as “non-MEAsections”), a water repellent treatment or a masking member or the likeis applied to the non-MEA sections beforehand. The MEA is then formedover the water-repellent treatment or masking member at the non-MEAsections, and on the outer surface of the heat transfer pipe at sectionsother than the non-MEA sections. In contrast, when the heat transferpipe does not function as an internal collector, an internal collectormust be arranged between the MEA and the heat transfer pipe. Therefore,the MEA is formed on the outer surface of the internal collector whichis arranged so as to contact the outer surface of the heat transferpipe. Moreover, one specific example of a method of sequentially formingthe MEA at intervals the distance of which corresponds to the length ofthe bent portion is to intermittently apply a melted or dissolvedcatalyst layer component and an electrolyte membrane component. Specificexamples of removing the MEA formed around the bent portion include amethod of focusing a laser beam on the non-MEA section and melting theMEA at that section with heat, a method of removing the MEA from thenon-MEA section by soaking that section in a solvent, and a method ofremoving the MEA formed on the surface of the masking member by removingthe masking member that was arranged on the non-MEA section in advance.

In this way, a tubular fuel cell module is manufactured which has asimplified seal structure achieved by limiting (reducing the number of)the inlets and outlets for the heating/cooling medium. This tubular fuelcell module thus has fewer seal portions and/or the locations where theheat transfer pipe passes through the seal portions than the relatedart, which improves the reliability of the seal. Hence, a manufacturingmethod of a tubular fuel cell module having improved seal reliability isable to be provided.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and further objects, features and advantages of theinvention will become apparent from the following description ofpreferred embodiments with reference to the accompanying drawings,wherein like numerals are used to represent like elements and wherein:

FIG. 1 is a perspective view schematically showing part of a moduleaccording to a first example embodiment of the invention;

FIG. 2 is a sectional view schematically showing an example of a portionof a heat transfer pipe and an MEA according to the invention;

FIG. 3 is a sectional view schematically showing a seal portion of themodule according to the first example embodiment of the invention;

FIG. 4 is a sectional view schematically showing a seal portion of arelated module;

FIG. 5 is a perspective view schematically showing part of a moduleaccording to a second example embodiment of the invention;

FIG. 6 is a perspective view schematically showing part of the moduleaccording to the first example embodiment of the invention;

FIG. 7 is a schematic of a simplified example of a manufacturing processof the module of the invention;

FIG. 8 is an external view of a tubular fuel cell module according to athird example embodiment of the invention;

FIG. 9A and FIG. 9B are sectional views of a seal portion of the moduleaccording to the third example embodiment of the invention and a sealportion of a related module, respectively;

FIG. 10 is a sectional view of a seal portion of a module according to afourth example embodiment of the invention; and

FIG. 11 is a schematic of an example of a manufacturing process of themodule of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A heat transfer pipe through which a heating/cooling medium flows isprovided in a tubular PEFC module in order to keep the temperature oftubular cells within an appropriate range. In a related tubular PEFCmodule (hereinafter simply referred to as “related module”), the heattransfer pipe is straight. As a result, the number of locations wherethe heat transfer pipe passes through a seal portion or seal member(which will be described later) formed between a reaction gas diffusionregion and a heating/cooling medium diffusion region is equal to thenumber of heat transfer pipes, which makes the seal structure complex.That is, in the related module, the heat transfer pipe passes throughthe seal portion at many locations so the distance between thoselocations is very short. As a result, the seal structure tends to becomplex, which tends to reduce the reliability of the seal and thus thestability of the tubular PEFC system (hereinafter simply referred to as“system”). One way to effectively improve the reliability of the seal isto reduce the number of locations where the heat transfer pipe passesthrough the seal portion and/or the number of seal portions (sealmembers). If the stability of the system can be ensured while reducingthe number of locations where the heat transfer pipe passes through theseal portion and the number of seal portions, then the system itself canbe made smaller and the output density improved.

The related module is also typically provided with one heat transferpipe for each tubular cell. The heat transfer pipes in the relatedmodule are also straight which means that there must be at least thesame number of seal portions as there are heat transfer pipes providedat the boundary between the reaction gas and the heating/cooling medium.That is, the related module is provided with many seal portions and thelocations where the heat transfer pipe passes through the seal portionsare all clustered within a small area so the seal structure not onlytends to be complex, but the seal also tends to be less reliable, whichtends to reduce the stability of the system. One way to effectivelyimprove the reliability of the seal is to reduce the number of sealportions. If the stability of the system can be ensured while reducingthe number of seal portions, then the system itself can be made smallerand the output density also improved.

The invention thus provides a tubular fuel cell module which improvesthe seal reliability by reducing the number of locations where the heattransfer pipes pass through the seal portions and the number of sealportions to less than the number in the related module, which isachieved by providing an S-shaped heat transfer pipe and an MEA formedon the heat transfer pipe or at least one tubular cell arranged on theheat transfer pipe (i.e., by arranging at least a portion of the tubularcells on the heat transfer pipe). In the same way, the invention alsoprovides a manufacturing method of that tubular fuel cell module.

Hereinafter, the tubular fuel cell module and the manufacturing methodthereof according to example embodiments of the invention will bedescribed in detail with reference to the drawings.

FIG. 1 is a perspective view schematically showing part of a moduleaccording to a first example embodiment of the invention. As shown inthe drawing, a tubular fuel cell module (hereinafter simply referred toas “module”) 100 according to the first example embodiment of theinvention includes a heat transfer pipe 1 formed so as to wind back andforth in a repeating S shape, MEAs 2 formed around the heat transferpipe, an external collector (not shown) arranged so as to contact eachMEA 2, and a collector 3 (see FIG. 6) arranged so as to contact bentportions 13 of the heat transfer pipe 1. The heat transfer pipe 1 of themodule 100 according to the first example embodiment of the inventionalso functions as an internal collector and is made by bending a singlestraight pipe, the base material of which is Cu—Ti clad material, toform the bent portions 13. The heat transfer pipe 1 thus includes firststraight portions 11, second straight portions 12, and the bent portions13 which connect the first straight portions 11 with the second straightportions 12. In this example embodiment, the heat transfer pipe 1 isformed so that the first straight portions 11, second straight portions12 and the bent portions 13 are arranged on a horizontal plane. Further,the first straight portions 11 and the second straight portions 12 arearranged substantially parallel. Reaction gas flow paths 16 are formedon the outer surface of the heat transfer pipe 1 for diffusing thereaction gas inside the MEAs 2. A hole 17 is also formed in the heattransfer pipe 1 through which a heating/cooling medium (such as water;hereinafter also referred to as “water”) flows. An inlet 14 and anoutlet 15 are both formed in the heat transfer pipe 1 of this exampleembodiment on the front side.

Thus, according to the module 100 of this example embodiment, both theinlet 14 and the outlet 15 of the heat transfer pipe 1 are positioned onthe front side. Therefore, the seal portion that provides a seal betweenthe heating/cooling medium flowing through the hole 17 in the heattransfer pipe 1 and the reaction gases need only be formed at the endportion on the front side of the MEAs 2, which reduces the number ofseal portions thus simplifying the seal structure. Moreover, because theinlet and outlet of the heat transfer pipe 1 are limited to only theinlet 14 and the outlet 15, only the inlet 14 and the outlet 15 passthrough a seal portion (which will be described later) formed between aheating/cooling medium diffusion region and a reaction gas diffusionregion. Accordingly, the heat transfer pipe passes through the sealportion at fewer locations, thereby enabling the seal structure to besimplified even more.

FIG. 2 is sectional view schematically showing a portion of the heattransfer pipe and the MEA shown in FIG. 1. The axial direction of theMEA is the direction perpendicular to the paper on which FIG. 2 isdrawn. Portions and members in FIG. 2 that are the same as those shownin FIG. 1 are denoted by the same reference numerals as they are in FIG.1 and descriptions thereof will be omitted. Hereinafter, the moduleaccording to the first example embodiment of the invention willdescribed with reference to FIGS. 1 and 2.

As shown in FIG. 2, the MEA 2 formed on the outer surface of the heattransfer pipe 1 includes an inside catalyst layer 21, an electrolytemembrane 22 formed on the outside of the inside catalyst layer 21, andan outside catalyst layer 23 formed on the outside of the electrolytemembrane 22. The inner surface of the inside catalyst layer 21 contactsthe outer surface of the heat transfer pipe 1. A hole 17 forming theheating/cooling medium flow path, as well as reaction gas flow paths 16are formed in the heat transfer pipe 1 which also functions as aninternal collector. In this way, with the module 100 in the firstexample embodiment of the invention, a reaction gas (either a gascontaining hydrogen or a gas containing oxygen) is supplied to theinside catalyst layer 21 via the reaction gas flow paths 16 formed inthe heat transfer pipe 1 and the electricity generated by the MEA 2 iscollected in the axial direction of the MEA 2 by the heat transfer pipe1. Further, the heat transfer pipe 1 contacts the inside catalyst layer21 so the temperature of the MEA 2 can be regulated by heating orcooling the MEA 2 by supplying cold or heated water or the like throughthe hole 17.

FIG. 3 is a sectional view schematically showing a seal portion of themodule according to the first example embodiment of the invention, andFIG. 4 is a sectional view schematically showing a seal portion of arelated module. The axial direction of the MEAs is the longitudinaldirection of the paper on which the drawings are drawn. FIG. 3 shows anexpanded view of a portion of the heat transfer pipe, the MEAs, and theseal portion (seal member) provided in the module according to the firstexample embodiment of the invention. The drawing shows the heat transferpipe having three bent portions, but the heat transfer pipe provided inthe module of the invention is not limited to this structure. On theother hand, FIG. 4 shows the structure of a related module having thesame number of straight heat transfer pipes as there are straightportions of the heat transfer pipe shown in FIG. 3, as well as the sealportions thereof. In FIGS. 3 and 4, constituent elements of the modulethat are the same as those shown in FIG. 1 will be denoted by the samereference numerals as they are in FIG. 1 and descriptions thereof willbe omitted. Also, in FIGS. 3 and 4, the intake ports and discharge portsfor the hydrogen, air (oxygen), and water are omitted. Further, thedrawings emphasize the seal portion arranged between the diffusionregion of the gas containing hydrogen and the diffusion region of thegas containing oxygen, i.e., between reaction gas diffusion regions, andthe seal portion arranged between the diffusion region of the gascontaining hydrogen and the heating/cooling medium diffusion region. Thestraight arrows in FIGS. 3 and 4 point in the direction in which thewater flows inside the heat transfer pipe.

As shown in FIG. 3, the module 100 in this example embodiment includesthe heat transfer pipe 1 and the MEAs 2 arranged on the outer surface ofthe heat transfer pipe 1. The heat transfer pipe 1 is made by bending asingle straight pipe, the base material of which is Cu—Ti clad material,to form the bent portions 13. The heat transfer pipe 1 thus includes thefirst straight portions 11 the second straight portions 12, and the bentportions 13 which connect the first straight portions 11 with the secondstraight portions 12. The module 100 in the drawing is structured suchthat the center portion is a diffusion region of the gas containingoxygen (hereinafter referred to as “oxygen diffusion region”) 7 and theregion on both sides of the oxygen diffusion region is a diffusionregion of the gas containing hydrogen (hereinafter referred to as“hydrogen diffusion region”) 6. Seal portions 5 a are provided betweenthe oxygen diffusion region 7 and the hydrogen diffusion regions 6, anda seal portion 5 b is formed between the hydrogen diffusion region 6 anda heating/cooling medium diffusion region (hereinafter also referred toas “water diffusion region”) 8. Thus the module 100 according to thisfirst example embodiment of the invention enables the structure of theseal portion to be simplified by having only the inlet 14 and the outlet15 of the heat transfer pipe 1 pass through the seal portion Sb.

In contrast, a related module 900 shown in FIG. 4 includes straight heattransfer pipes 10 and MEAs 2 arranged on the outer peripheral surfacesof the heat transfer pipes 10. Similar to the module 100 shown in FIG.3, the module 900 in FIG. 4 is structured such that the center portionis the oxygen diffusion region 7, the region on both sides of the oxygendiffusion region 7 is the hydrogen diffusion region 6, the seal portions5 a are arranged between the oxygen diffusion region 7 and the hydrogendiffusion regions 6, and seal portions 95 b and 95 b are arrangedbetween the hydrogen diffusion region 7 and the water diffusion regions8. In the related module 900, when the number of heat transfer pipes 10is “t”, the number of locations where the heat transfer pipes 10 passthrough each seal portion 95 b is also “t”, which complicates the sealstructure and in turn tends to make the seal less reliable.

As shown in FIGS. 3 and 4, the heat transfer pipe 1 of the module 100according to the first example embodiment of the invention is formedwinding back and forth in a repeating S shape which both increases thedistance between the locations where the heat transfer pipe 1 passesthrough the seal portion Sb, as well as reduces the number of thoselocations, thereby improving the reliability of the seal. Furthermore,the module 100 according to the first example embodiment of theinvention also obviates the need to provide a heating/cooling mediumdiffusion region on both ends of the module, which reduces the number ofseal portions and enables the module to be made smaller, as well asimproves the output density of the module 100.

In the foregoing description, the inlet and the outlet of the heattransfer pipe are positioned on the same side with respect to the centerin the axial direction of the MEAS. The heat transfer pipe in the moduleof the invention is not limited to this structure, however.Alternatively, the inlet and the outlet of the heat transfer pipe may bepositioned on opposite sides with respect to the center in the axialdirection of the MEAs. Positioning the inlet and the outlet of the heattransfer pipe on the same side with respect to the center in the axialdirection of the MEAs, however, makes it easier to make the modulesmaller.

Also, in the foregoing module 100, the heat transfer pipe 1 includes thefirst straight portions 11, the second straight portions 12 and the bentportions 13 arranged on a horizontal plane. The heat transfer pipe inthe module of the invention is not limited to this arrangement, however.FIG. 5 shows another example of how the heat transfer pipe in the moduleof the invention can be arranged.

FIG. 5 is a perspective view schematically showing part of a moduleaccording to a second example embodiment of the invention. Theconstituent elements of the module shown in FIG. 5 that are the same asthose shown in FIG. 1 are denoted by the same reference numerals used inFIG. 1 and descriptions of those elements will be omitted.

As shown in FIG. 5, a module 200 according to the second exampleembodiment of the invention includes a heat transfer pipe 1 a, MEAs 2formed on the outside of the heat transfer pipe 1 a, an externalcollector (not shown) arranged so as to contact each MEA 2, and acollector (also not shown) arranged so as to contact bent portions 13 aof the heat transfer pipe 1 a. As shown in the drawing, the heattransfer pipe 1 a according to this second example embodiment is suchthat first straight portions 11, second straight portions 12, and thebent portions 13 a that connect the first straight portions 11 with thesecond straight portion 12 are formed in a generally cylindrical shapeand an inlet 14 and an outlet 15 of the heat transfer pipe 1 a areadjacent to one another. In this example embodiment, the heat transferpipe 1 a also functions as an internal collector and is made by bendinga single straight pipe, the base material of which is Cu—Ti cladmaterial, to form the bent portions 13 a. Reaction gas flow paths 16 areformed on the outer surface of the heat transfer pipe 1 for diffusingthe reaction gas inside the MEAs 2. A hole 17 is also formed in the heattransfer pipe 1 a through which a heating/cooling medium such as waterflows.

Thus the module 200 according to this second example embodiment enablesthe structure of the seal to be simplified by having the inlet 14 andthe outlet 15 of the heat transfer pipe 1 a adjacent to one another.

Moreover, in this module 200 according to the second example embodiment,the heat transfer pipe 1 a is formed generally cylindrical whichimproves the strength of the module on the whole, as well as makes themodule easier to handle. On the other hand, with the module 100according to the first example embodiment, the heat transfer pipe 1 isdisposed on a horizontal plane which makes it easily to ensure spacebetween the MEAs 2. Also in this case, there is no space in the centeras there is when the heat transfer pipe 1 a is formed generallycylindrical, which makes it easier to improve the output density.Accordingly, from the viewpoint of improving output density, the module100 according to the first example embodiment is preferable. On theother hand, from the viewpoint of making the module easier to handle,the module 200 according to the second example embodiment is preferable.

To make to the structures of the modules according to the exampleembodiments of the invention easier to understand, the collector whichis arranged contacting the bent portions has been omitted in FIGS. 1 to5. Although not shown, this collector is provided in the modulesaccording to the example embodiments of the invention to improve powercollecting efficiency in the direction; intersecting the axial directionof the MEAs. FIG. 6 schematically shows a module provided with thecollector arranged contacting the bent portions.

FIG. 6 is a perspective view schematically showing an example of themodule according to the first example embodiment of the invention. Inthe drawing, the module 100 of the invention is provided with acollector 3 that contacts the bent portions 13 on the side opposite theside on which the inlet 14 and the outlet 15 of the heat transfer pipe 1are located. Thus the module according to this example embodiment of theinvention is provided with a collector that contacts the bent portionsof the heat transfer pipe, which improves power collecting efficiency inthe direction intersecting the axial direction of the MEAs.Incidentally, the example shown in FIG. 6 is one in which the collector3 is arranged so as to contact the bent portions 13 on the side oppositethe side on which the inlet 14 and the outlet 15 of the heat transferpipe 1 are located. The invention is not limited to this structure,however. Alternatively, the collector may be arranged so as to contactthe bent portions on the same side as the side on which the inlet andthe outlet of the heat transfer pipe are located, or a first collectormay be arranged so as to contact the bent portions on one side and asecond collector may be arranged so as to contact the bent portions onthe other side. Of these structures, the structure in which the firstcollector and the second collector are provided is preferable from theviewpoint of further improving the power collecting efficiency.

In the foregoing description, hydrogen is supplied to the inside of theMEAs and air (oxygen) is supplied to the outside of the MEAs, but theinvention is not limited to this. Conversely, air may be supplied to theinside of the MEAs and hydrogen supplied to the outside of the MEAs.

FIG. 7 shows a simplified example of a method for manufacturing thetubular fuel cell module according to the foregoing example embodimentsof the invention. The module of the invention may also be provided witha heat transfer pipe that only serves to heat or cool the MEA, but tomake it easier to make the module smaller by reducing the number ofconstituent members, the heat transfer pipe preferably also functions asan internal collector as described above. Therefore, an example of amanufacturing process of a module provided with a heat transfer pipethat also functions as an internal collector will be described. Further,in the manufacturing method according to the example embodiment of theinvention, two methods are conceivable for forming the MEAs on thesurfaces of the straight portions of the heat transfer pipe while havingthe surface of the bent portions of the heat transfer pipe be uncovered,as shown in FIG. 1, for example. These methods are: (1) a method offorming MEAs only on those surfaces to be covered with MEAs and notforming MEAs on surfaces not to be covered with MEAs (i.e., non-MEAsections), and (2) a method of forming an MEA on the outer surface ofthe entire heat transfer pipe and then removing the MEA from the non-MEAsections. A specific example (2a) of the second method (2) is to formthe MEA after first arranging a masking member on the non-MEA sections,and then remove the masking member (with the MEA formed thereon) afterthe MEA is formed. Hereinafter, the method of (2a) will be described indetail while only a general outline of the other methods will bedescribed. Hereinafter, the manufacturing method of the tubular fuelcell module according to the example embodiment of the invention will bedescribed while using the reference numerals used in FIGS. 1 to 3 asappropriate. When the heat transfer pipe also functions as an internalcollector, the surface of the heat transfer pipe that contacts theheating/cooling medium (such as the inside surface) may be coated withinsulating material to prevent electrical leakage and the like.

According to the manufacturing method of the tubular fuel cell accordingto the example embodiment of the invention, a straight heat transferpipe having a hole 17 and grooves 16 is first prepared and an MEA 2 isformed on the outer surface of the heat transfer pipe. The constituentmaterial of the electrolyte membrane 22 of the MEA 2 may be, forexample, a fluorine-containing ion-exchange resin. The constituentmaterial of the inside catalyst layer 21 and the outside catalyst layer23 may be, for example, a mixture of fluorine-containing ion-exchangeresin and platinum-carrying carbon.

To form the MEA 2 on the outer surface of the straight heat transferpipe, the masking member is arranged (step S1; masking process) on theouter surface of the non-MEA sections of the heat transfer pipe (i.e.,the sections corresponding to the bent portions 13 and the areas nearthe inlet 14 and the outlet 15 of the heat transfer pipe), for example.Then the inside catalyst layer 21 is formed on the outer surface of theheat transfer pipe of which a portion of the outer surface is coveredwith the masking member by, for example, applying a catalyst ink inwhich a catalyst such as platinum-carrying carbon is dispersed in asolution including fluorine-containing ion-exchange resin or the likethat has been dissolved using an organic solvent, and then drying thatcatalyst ink. Next, the electrolyte membrane 22 is formed by applying afluorine-containing ion-exchange resin or the like (hereinafter referredto as “electrolyte component”) that has been dissolved using an organicsolvent to the surface of the inside catalyst layer 21 and drying thatelectrolyte component. Then an outside catalyst layer 23 is formed byapplying the catalyst ink to the surface of the electrolyte membrane 22and drying it, thus resulting in an MBA 2 formed on the outer surface ofthe heat transfer pipe (step S2; MEA forming process).

In this way, after the MEA 2 is formed on the outer surface of thestraight heat transfer pipe, the bent portions 13 are formed at thesections where the masking member was arranged in step S1, whichcorrespond to the bent portions, by sequentially bending those sections(step S3; bent portion forming process). Then after step S3, the module100 as shown in FIG. 1 (hereinafter also referred to as “bent body”) ismade by removing the masking member, thereby removing the MBA 2 formedon the outer surface of the non-MEA sections (step S4; removal process).After the bent body is formed in that step, the seal portion 5 a whichseparates the hydrogen from the air (oxygen) is then formed, and theseal portion 5 b is formed around the inlet 14 and the outlet 15 of theheat transfer pipe (step S5; seal portion forming process). After stepS5 is complete, the module of the invention can be manufactured througha process such as placing the bent body provided with the seal portionsthat was manufactured in steps S1 to S5 into a predetermined case.Because the module 100 manufactured through these steps is provided withthe S-shaped heat transfer pipe 1, the number of seal portions can bereduced. Therefore, this example embodiment of the invention is able toprovide a manufacturing method of a tubular fuel cell module havingincreased seal reliability.

Heretofore, method (2a) above was described as a manufacturing method ofthe example embodiment of the invention, but the manufacturing method ofthe invention is not limited to that method. One specific example of themethod of forming MEAs only on those surfaces to be covered with MEAsand not forming MEAs on surfaces not to be covered with MEAs (i.e.,method (1) above) is to intermittently apply the catalyst ink andelectrolyte component to the outer surface of the straight heat transferpipe while avoiding the non-MEA sections (i.e., intermittentapplication). Also, other specific examples of the method of firstforming an MEA on the outer surface of the entire heat transfer pipe andthen removing the MEA from the non-MBA sections (i.e., method (2) above)include soaking only the non-MEA sections in a solvent to dissolve andremove the MBA from those sections, or focusing a laser beam on only thenon-MBA sections to melt and remove the MEA from those sections. Inaddition, another specific example of method (2) above is to apply awater repellent treatment which makes it difficult for the MEA to formto the non-MEA sections beforehand and then removing the MEA at thosesections by cleaning them using high pressure or the like. When theintermittent application method is used here, the masking member may beapplied to the non-MEA sections beforehand and then removed afterintermittent application.

When using a masking member in the manufacturing method of theinvention, the material of the masking member and the manner of maskingare not particularly limited as long as they inhibit the catalyst inkand electrolyte component from adhering to the outer surface of the heattransfer pipe. Specific examples of the material of which the maskingmember is made include polyethylene resin, polypropylene resin, and ablend of the two.

In the foregoing example embodiment, an example was given in which anMEA is formed on the outside of a heat transfer pipe having a hole andgrooves, and the MEA includes a hollow inside catalyst layer, a hollowelectrolyte membrane, and a hollow outside catalyst layer havingsubstantially the same axial center as the heat transfer pipe. Themodule of the invention, however, is not limited to this. That is, themodule of the invention may alternatively include a bent body in which,for example, a plurality of internal collectors formed of wire rods arearranged contacting the outer surface of a straight portion of a heattransfer pipe formed in a repeating S shape, a plurality of wire rods onwhich an inside catalyst layer is formed are arranged (provided) on theoutside of the internal connectors, and an electrolyte membrane and anoutside catalyst layer are formed in that order on the outside of thewire rods having the inside catalyst layer. With this structure as well,as long as the heat transfer pipe is S shaped, the number of sealportions can be reduced, making it possible to provide both a tubularfuel cell module having improved seal reliability and the manufacturingmethod of that tubular fuel cell module.

FIG. 8 is an external view schematically showing a portion of a tubularfuel cell module according to a third example embodiment of theinvention. As shown in the drawing, a module 300 according to the thirdexample embodiment of the invention includes a plurality of tubular fuelcell cells 31, and a heat transfer pipe 32 arranged so as to contact theouter peripheral surfaces of the plurality of tubular fuel cell cells31. The heat transfer pipe 32 is made by bending a single straight pipe,the base material of which is Cu—Ti clad material, to form bent portions32 c, and thus includes first straight portions 32 a, second straightportions 32 b, and the bent portions 32 c that connect the firststraight portions 32 a and the second straight portions 32 b. An inlet32 x and an outlet 32 y of the heat transfer pipe 32 are positioned onthe upper side of the drawing, and are formed such that the direction inwhich they open is at a 90 degree angle from the axial direction of thefirst straight portions 32 a and the second straight portions 32 b. Thefeat transfer pipe 31 according to the third example embodiment alsofunctions as an external collector.

Thus, in the module 300 according to this example embodiment, the inlet32 x and the outlet 32 y of the heat transfer pipe 32 are bothpositioned on the upper side in the drawing. As a result, the sealportions which provide a seal between the reaction gases and theheating/cooling medium flowing through the heat transfer pipe 32 (to bedescribed later) need only be formed at the end portions of the tubularcells 31 that are on the upper side in the drawing, which enables theseal structure to be simplified. Moreover, because the inlet and outletof the heat transfer pipe 32 are limited to only the inlet 32 x and theoutlet 32 y, the seal portion provided between the heating/coolingmedium and the reaction gas diffusion region need only be arranged nearthe inlet 32 x and the outlet 32 y, thereby enabling the seal structureto be simplified even more. In addition, the inlet 32 x and the outlet32 y of the heat transfer pipe 32 both face to the outside so thedirection of the openings of the inlet 32 x and the outlet 32 yintersect the axial direction of the tubular cells 31. As a result, theseal portion that provides a seal between the heating/cooling medium andthe reaction gas can be formed so that the perpendicular line of theseal portion extends in a direction other than the axial direction ofthe tubular cells 31, which enables the number of seal portions formedin the axial direction of the tubular cells 31 to be reduced.Simplifying the seal structure in this way improves the reliability ofthe seals in the module 300.

FIG. 9A and FIG. 9B are sectional views schematically showing structuralexamples of a seal portion in the module according to the third exampleembodiment of the invention and a seal portion in a related module,respectively. FIG. 9A shows an enlarged view of only a portion of theseal portion (seal member), the tubular cell, and the heat transfer pipeprovided in the module according to the third example embodiment of theinvention. In the drawing, the heat transfer pipe is shown having threebent portions, though the heat transfer pipe provided in the module ofthe invention is not limited to this structure. FIG. 9B on the otherhand shows the structure of a related module provided with the samenumber of straight heat transfer pipes as there are straight portions ofthe heat transfer pipe shown in FIG. 9A, as well as the structure of theseal portion of that related module. In FIGS. 9A and 9B, constituentelements of the module that are the same as those shown in FIG. 8 willbe denoted by the same reference numerals as they are in FIG. 8 anddescriptions thereof will be omitted. Also, in FIGS. 9A and 9B, theintake ports and discharge ports for the hydrogen, air (oxygen), andwater are omitted and the seal portion arranged between the hydrogendiffusion region and the air (oxygen) diffusion region, i.e., thereaction gas diffusion regions, and the seal portion arranged around theheat transfer pipe are shown emphasized. The straight arrows in FIGS. 9Aand 9B point in the direction in which the heating/cooling medium flowsinside the heat transfer pipe.

As shown in FIG. 9A, a module 300 according to the third exampleembodiment of the invention includes the heat transfer pipe 32 and theplurality of tubular cells 31 arranged on the outer peripheral surfaceof the heat transfer pipe 32. The heat transfer pipe 32 is made bybending a single straight pipe, the base material of which is Cu—Ti cladmaterial, to form bent portions 32 c. The heat transfer pipe 32 thusincludes first straight portions 32 a, second straight portions 32 b,and the bent portions 32 c which connect the first straight portions 32a with the second straight portions 32 b. The module 300 in the drawingis structured such that the center portion is an oxygen diffusion region37 and the both end portions are hydrogen diffusion regions 36. A sealportion 35 a is provided between the oxygen diffusion region 37 and eachhydrogen diffusion region 36, and a seal portion 35 b is formed aroundthe inlet 32 x and the outlet 32 y of the heat transfer pipe 32. Thusthe module 300 of the third example embodiment enables the hydrogendiffusion region to be sealed by arranging the seal portion 35 b formedaround the heat transfer pipe 32 only at the inlet 32 x and the outlet32 y of the heat transfer pipe 32.

In contrast, a related module 90 shown in FIG. 9B includes straight heattransfer pipes 33 and tubular cells 31 arranged on the outer peripheralsurface of the heat transfer pipes 33. Similar to the module 300 shownin FIG. 9A, the module 90 in FIG. 9B is structured such that the centerportion is the oxygen diffusion region 37 and both end portions arehydrogen diffusion regions 36, the seal portion 35 a is arranged betweenthe oxygen diffusion region 37 and both of the hydrogen diffusionregions 36, seal portions 395 b are arranged around the heat transferpipes 33 in the hydrogen diffusion regions 36. In the related module 90,when the number of heat transfer pipes 33 is “t”, the number oflocations where the heat transfer pipes 33 pass through the two sealportions 395 b must be “2t”, so the number of locations where the heattransfer pipes 33 pass through the two seal portions 395 b increasesdepending on the number of heat transfer pipes 33.

As shown in FIGS. 9A and 9B, the heat transfer pipe 32 of the module 300according to the third example embodiment of the invention is formedwinding back and forth in a repeating S shape which reduces the numberof locations where the heat transfer pipe 32 passes through the sealportions 35 b, thereby improving the reliability of the seal, as well asenabling the module 300 to be made smaller and improving the outputdensity of the module 300.

In the foregoing third example embodiment, the inlet and the outlet ofthe heat transfer pipe are positioned on the same side with respect tothe center in the axial direction of the tubular cell. The heat transferpipe in the module of the invention is not limited to this structure,however. Alternatively, the inlet and the outlet of the heat transferpipe may be positioned on opposite sides with respect to the center inthe axial direction of the tubular cell. Positioning the inlet and theoutlet of the heat transfer pipe on the same side with respect to thecenter in the axial direction of the tubular cell, however, makes iteasier to connect the inlet of the heat transfer pipe provided in onemodule with the outlet of a heat transfer pipe provided in anothermodule.

Also, in the third example embodiment, the heat transfer pipe is formedso that the first straight portions, the second straight portions andthe bent portions are arranged in an horizontal plane, and the inlet andthe outlet of the heat transfer pipe are formed facing the outside in adirection intersecting (i.e., more specifically, in a directionsubstantially orthogonal to) the axial direction of the first and secondstraight portions of the heat transfer pipe when viewed from above thehorizontal plane (see FIGS. 8, 9A and 9B). The heat transfer pipe is notlimited to this structure, however. FIG. 10 shows another example of howthe heat transfer pipe in the module of the invention can be arranged.

FIG. 10 is a sectional view schematically showing an example structureof a seal portion of a module according to a fourth example embodimentof the invention. The drawing shows only a portion of the seal portion,the tubular cell, and the heat transfer pipe enlarged. FIG. 10, whichcorresponds to FIG. 9A, shows the heat transfer pipe having three bentportions, but the heat transfer pipe provided in the module of theinvention is not limited to this structure. In FIG. 10, constituentelements of the module that are the same as those shown in FIG. 9A willbe denoted by the same reference numerals as they are in FIG. 9A anddescriptions thereof will be omitted. Also, in FIG. 10, the intake portsand discharge ports for the hydrogen, air, and water are omitted and theseal portion arranged between the hydrogen diffusion region and the air(oxygen) diffusion region, as well as the seal portion arranged aroundthe heat transfer pipe are shown emphasized. The straight arrows in FIG.10 point in the direction in which the heating/cooling medium flowsinside the heat transfer pipe.

As shown in FIG. 10, a module 400 according to the fourth exampleembodiment of the invention includes a heat transfer pipe 32′ and aplurality of tubular cells 31 arranged on the outer peripheral surfaceof the heat transfer pipe 32′. The heat transfer pipe 32′ is made bybending a single straight pipe, the base material of which is Cu—Ti cladmaterial, to form bent portions 32 c, and thus includes first straightportions 32 a, second straight portions 32 b, and the bent portions 32 cwhich connect the first straight portions 32 a with the second straightportions 32 b. The module 400 in the drawing is structured such that thecenter portion is an oxygen diffusion region 37 and both end portionsare hydrogen diffusion regions 36. A seal portion 35 a is providedbetween the oxygen diffusion region 37 and each hydrogen diffusionregion 36, and a seal portion 35 b′ is formed around the inlet 32 x andthe outlet 32 y of the heat transfer pipe 32′. Therefore, even in themodule 400 in which the direction that the inlet 32 x and the outlet 32y of the heat transfer pipe 32′ open are the same as the axial directionof the first straight portions 32 a and the second straight portions 32b, the length of the seal portion 35 b′ between the inlet 32 x and theoutlet 32 y of the heat transfer pipe 32′ is able to be greater than itwas conventionally. As a result, the number of locations where the heattransfer pipe 32′ passes through the seal portion 35 b′ can be reducedso the seal structure can be simplified. That is, the module 400according to this fourth example embodiment of the invention has fewerlocations where the heat transfer pipe passes through the seal portionthan the related module, which not only improves the reliability of theseal, but also enables the module to be smaller and improves the outputdensity of the module.

FIG. 11 shows a simplified example of a manufacturing process of themodule according to the third or fourth example embodiment describedabove. In the module of the invention, a heat transfer pipe may beprovided which functions only to selectively heat and cool (i.e.,regulate the temperature of) the tubular cell, but to make it easier tomake the module smaller by reducing the number of constituent members,the heat transfer pipe provided may also serve as the exteriorcollector, as described above. When the heat transfer pipe also servesas the exterior collector in this way, the surface (e.g., the insidesurface) of the heat transfer pipe that contacts the heating/coolingmedium may be covered with insulating material to prevent electricalleakage Hereinafter, an example of a manufacturing process of a moduleprovided with a heat transfer pipe that also serves as the externalcollector will be described.

The module according to the third or fourth example embodiment describedabove is provided with a heat transfer pipe and a plurality of tubularcells that are arranged on the outer peripheral surface of the heattransfer pipe. Thus, the tubular cells must be made when manufacturingthe module. The constituent material of the electrolyte membraneprovided in the tubular cells may be, for example, a fluorine-containingion-exchange resin. Also, the constituent material of the catalyst layermay be, for example, a mixture of fluorine-containing ion-exchange resinand platinum-carrying carbon. The tubular cells are then made by, forexample, forming a catalyst layer on the surface of an internalcollector in which spaces (e.g., grooves) for allowing reaction gas toflow are formed in the outer peripheral surface of Cu—Ti clad material,for example. The catalyst layer is formed by applying a catalyst ink inwhich a catalyst such as platinum-carrying carbon is dispersed in asolution including fluorine-containing ion-exchange resin or the likethat has been dissolved using an organic solvent, and then drying thatcatalyst ink. Next, an electrolyte membrane is formed by applying afluorine-containing ion-exchange resin or the like that has beendissolved using an organic solvent to the surface of the catalyst layerand drying it. Then a catalyst layer is formed by applying the catalystink to the surface of the electrolyte membrane and drying it. Thus, anMEA which includes a catalyst layer, an electrode membrane and anothercatalyst layer is made on the outer peripheral surface of the internalcollector. In this way, the tubular cells which are arranged on theouter peripheral surface of the heat transfer pipe are made (step S10;tubular cell making process).

Once the tubular cells have been manufactured by the method describedabove, for example, the plurality of tubular cells are then arranged(i.e., fixed) on the outer peripheral surface of the straight heattransfer pipe at intervals that enable the bent portions to be formed(step S20; tubular cell arranging process). Once the plurality oftubular cells have been arranged at the predetermined intervals on theouter peripheral surface of the heat transfer pipe, the heat transferpipe is then formed into a repeating S shape by sequentially bending itat locations where the tubular cells are not arranged (step S30; bentportion forming process). Next, seal portions which separate thehydrogen from the air (oxygen) are then formed, as are the seal portionsnear the inlet and the outlet of the heat transfer pipe (step S40; sealportion forming process). After step S40 is complete, the module in thisexample embodiment of the invention can be manufactured through aprocess such as placing the article manufactured according to steps S10to S40 into a predetermined case.

In the foregoing example embodiments, a module provided with a heattransfer pipe made of Cu—Ti clad material was given as an example, butthe constituent material of the heat transfer pipe of the invention isnot limited to this. For example, the constituent material of the heattransfer pipe used in the module of the invention may be Au or Pt or thelike instead of Cu—Ti clad material.

Furthermore, in the foregoing description, a heat transfer pipe havingthe first straight portions, the second straight portions, and the bentportions is made by bending a single straight pipe to form the bentportions. However, the heat transfer pipe of the invention is notlimited to this. For example, the heat transfer pipe of the inventionmay also be formed by connecting U-shaped pipes with straight pipes, forexample. While a heat transfer pipe having this kind of structure alsoenables the number of seal portions between the hydrogen diffusionregion and heating/cooling medium and/or the number of locations wherethe heat transfer pipe passes through the seal portions to be reduced,it also requires a process of connecting the straight pipes to theU-shaped pipes during manufacturing. Therefore, from the viewpoint ofimproving workability when manufacturing the module of the invention, itis preferable to form the bent portions by bending a straight heattransfer pipe. The heating/cooling medium flowing through the heattransfer pipe provided in the module of the invention may be, forexample, chilled water, ethylene glycol, or a mixture of the two whencooling the tubular cells, and heated water or the like when heating thetubular cells.

In the third example embodiment (see FIG. 8) described above, sixtubular cells are arranged around each straight portion of the heattransfer pipe, but the invention is not limited to this. That is, thenumber of tubular cells arranged around the straight portions may be anumber that is appropriate taking various factors into account, such asthe diffusivity of the reaction gas and the cooling efficiency of thetubular cells.

Also, the constituent material of the seal portions provided in themodule of the invention may be, for example, a thermosetting resin suchas epoxy, or an adhesive that hardens by 2-liquid mixing, such as aheat-resistant epoxy based 2-liquid thermosetting adhesive or the like.

In addition, in the foregoing example embodiments, a module wasdescribed in which an air (oxygen) diffusion region is arranged in thecenter portion of the tubular cells and a hydrogen diffusion region isarranged at both end portions of the air diffusion region. However, theinvention is not limited to this. Alternatively, the hydrogen diffusionregion may be arranged in the center portion and the oxygen diffusionregion may be arranged at both end portions.

While the invention has been described with reference to exemplaryembodiments thereof, it is to be understood that the invention is notlimited to the exemplary embodiments or constructions. To the contrary,the invention is intended to cover various modifications and equivalentarrangements. In addition, while the various elements of the exemplaryembodiments are shown in various combinations and configurations, whichare exemplary, other combinations and configurations, including more,less or only a single element, are also within the spirit and scope ofthe invention.

1.-2. (canceled)
 3. The tubular fuel cell module according to claim 17,wherein the heat transfer pipe serves as an internal collector, and aninner peripheral surface of the MEA contacts the at least one of theouter peripheral surface of the first straight portion and the outerperipheral surface of the second straight portion.
 4. (canceled)
 5. Thetubular fuel cell module according to claim 18, wherein the heattransfer pipe serves as an external collector.
 6. The tubular fuel cellmodule according to claim 16, wherein the first straight portion, thesecond straight portion, and the bent portion are formed by bending asingle heat transfer pipe.
 7. The tubular fuel cell module according toclaim 16, wherein an inlet and an outlet of the heat transfer pipe arepositioned on the same side with respect to the center in an axialdirection of the tubular cell.
 8. The tubular fuel cell module accordingto claim 16, wherein the tubular cell comprises a plurality of tubularcells, at least a portion of each tubular cell is arranged on one of thefirst straight portion and the second straight portion, and at least oneof the plurality of tubular cell is arranged on each of the firststraight portion and the second straight portion.
 9. The tubular fuelcell module according to claim 16, wherein the first straight portionand the second straight portion are arranged on a horizontal plane, andan inlet and an outlet of the heat transfer pipe are formed facing theoutside in a direction intersecting an axial direction of at least oneof the first straight portion and the second straight portion whenviewed from above the horizontal plane.
 10. The tubular fuel cell moduleaccording to claim 16, wherein the first straight portion, the secondstraight portion and the bent portion are arranged in a plane and thefirst straight portion and the second straight portion are arrangedsubstantially parallel to one another.
 11. The tubular fuel cell moduleaccording to claim 16, wherein the first straight portion, the secondstraight portion and the bent portion respectively comprise a pluralityof first straight portions, a plurality of second straight portions, anda plurality of bent portions, and the plurality of first straightportions, the plurality of second straight portions and the plurality ofbent portions are formed in a generally cylindrical shape.
 12. Thetubular fuel cell module according to claim 17, wherein the heattransfer pipe includes a reaction gas flow path on an outer surface ofthe heat transfer pipe, for diffusing reaction gas inside the MEA.
 13. Amanufacturing method of a tubular fuel cell module provided with atleast one hollow MEA, and a heat transfer pipe through which flows aheating/cooling medium that selectively heats and cools the MEA,comprising: forming the MEA around a straight tubular member; andforming a heat transfer pipe that includes a first straight portion, asecond straight portion, and a bent portion that connects the firststraight portion with the second straight portion, by bending thestraight tubular member, wherein the MEA is formed sequentially atintervals the distance of which corresponds to at least the length ofthe bent portion.
 14. A manufacturing method of a tubular fuel cellmodule provided with at least one hollow MEA, and a heat transfer pipethrough which flows a heating/cooling medium that selectively heats andcools the MEA, comprising: forming the MEA around a straight tubularmember; forming a heat transfer pipe that includes a first straightportion, a second straight portion, and a bent portion that connects thefirst straight portion with the second straight portion, by bending thestraight tubular member; and removing the MEA formed at least around thebent portion.
 15. The tubular fuel cell module according to claim 16,wherein the first straight portion and the second straight portionrespectively comprise a plurality of first straight portions and aplurality of second straight portions, the tubular fuel cell modulefurther comprising: a seal portion that seals between a reaction gas andthe heating/cooling medium, wherein the number of locations where theheat transfer pipe passes through the seal portion is smaller than thesum of the number of the plurality of first straight portions and thenumber of the plurality of second straight portions.
 16. A tubular fuelcell module comprising: a tubular cell of a tubular fuel cell; and aheat transfer pipe through which flows a heating/cooling medium thatselectively heats and cools the tubular cell, the heat transfer pipeincluding a first straight portion, a second straight portion, and abent portion that connects the first straight portion with the secondstraight portion, wherein at least a portion of the tubular cell isarranged on at least one of the first straight portion and the secondstraight portion.
 17. A tubular fuel cell module comprising: a hollowMEA; and a heat transfer pipe through which flows a heating/coolingmedium that selectively heats and cools the MEA, the heat transfer pipeincluding a first straight portion, a second straight portion, and abent portion that connects the first straight portion with the secondstraight portion, wherein the MEA is arranged on at least one of anouter peripheral surface of the first straight portion and an outerperipheral surface of the second straight portion.
 18. A tubular fuelcell module comprising: a tubular cell of a tubular fuel cell; and aheat transfer pipe through which flows a heating/cooling medium thatselectively heats and cools the tubular cell, the heat transfer pipeincluding a first straight portion, a second straight portion, and abent portion that connects the first straight portion with the secondstraight portion, wherein an outer peripheral surface of the tubularcell contacts the outer peripheral surface of at least one of the firststraight portion and the second straight portion.